const EventEmitter = require('events').EventEmitter;
function Dog(name,energy){
  let _name = name,
      _energy = energy,
      that = this;

  //调用基类的构造函数
  EventEmitter.call(this);

  let timer = setInterval(()=>{
    if(_energy > 0){
      that.emit('bark');
      _energy--;
    }else{
      clearInterval(timer);
    }
  },1000);

  this.name = ()=> _name;
  this.energy = ()=> _energy;
}
Dog.prototype = EventEmitter.prototype;
module.exports= Dog;
